I'd recommend against the 18-200VR for general use; although the overall image quality isn't bad, the fact that it slows down to f/5.6 at the telephoto end makes it more challenging to get captures without flash in lower light situations such as church interiors and reception venues.
Shooting at f/5.6 in these circumstances will lead you to either
a) upping your ISO setting and introducing noise to the image
b) slowing your shutter speed and introducing subject motion blur, or
c) both of the above
In properly lit situations, wether flash or natural light, the 18-200VR is more than adequate... but you oftentimes don't have that luxury when shooting weddings, which is why I would advise against using anything less than a lens which has a constant f/2.8 aperture throughout it's range.
On a personal level I'd love to get my hands on an 18-200 to give it a whirl, since I think it would be a great general walkabout lens for me outside of work related photography. I guess a lot of people feel the same since it's easier to get a winning lottery ticket than one of these lenses
